There are tons of cliché wisdoms about nutrition: Eat at least five servings of fruit every day. Drink plenty of water. Eat three separate meals. Do this, do that, that's "healthy." What's true? Buffer co-founder Leo Widrich explores the science behind what we eat and how it affects the brain's performance.

Every seven years, the body will change completely. This means that each and every one of your cells will have been renewed and exchanged for another one that your body has produced. I am always amazed by this. Science suggests that this gives us a unique chance to change and erase any mistakes we've made in the past. How? Through a focus on the food we eat. Fortunately we don't have to wait seven years. Day-to-day changes in our diet can have a massive impact on our productivity. Something like this:

How food interacts with your brain

One of the most fascinating things about eating is how various ingredients enter the brain through your blood stream. The elements that make it through to power your brain will help you to either focus or lose focus.

Most of what we eat will be broken down to one thing: Glucose. Glucose is our fuel, keeping our brains awake and alert. So at all times, we have a certain glucose level in our blood (kind of like gasoline in a car).

The most important part here is that we are in full control of how we release glucose to our blood and our brains. Certain foods release glucose quickly, while others do so more slowly, yet sustainably. Researcher Leigh Gibson found this to be optimal:

"The brain works best with about 25 grams of glucose circulating in the blood stream—about the amount found in a banana."

The way you can get those 25 grams of glucose into your blood stream is pretty easy. You can eat a donut. You can eat a small bowl of oats. There is virtually no difference in the very short term for your brain activity.

Over the stretch of a normal 8-hour day however, the differences are spectacular. After eating the donut, we will release glucose into our blood very quickly. We will have about 20 minutes of alertness. Then our glucose level will drop rapidly, leaving us unfocused and easy to distract. It's like putting the foot down on the gas pedal until you've used all your fuel.

The oats, on the other hand, release their sugar as glucose much slower. This means we will have a steady glucose level, better focus, and higher attention levels. Another important factor are your Leptin levels. Leptin will signal to your brain how full you are. If you are now guessing that a donut won't signal your brain to be full for a long time, while oats will, well, you are right.

What we are also measuring here as the difference between a donut and a bowl of oats is called your "glycemic index," coined by the Franklin Institute:

All the children in a class were told to skip breakfast one morning, and then, by random assignment, half of the children were given a good breakfast at school. The others got nothing. During the first part of the morning, the children who got breakfast learned more and misbehaved less (as judged by monitors who didn't know which children had eaten). Then, after all the students were given a healthy snack in the middle of the morning, the differences disappeared as if by magic.

Eric Barker, one of the best productivity bloggers out there, put it like this: "Across the board, yeah, food puts you in a better mood. To be more exact, research has shown that two cheeseburgers = one orgasm."

Using context to control your eating is one of the most important aspects. If you are like me, you always end up eating portions that are too big, which makes me overly full at lunch and very tired a few hours afterwards.

One of the best proven techniques here is to eat from a smaller plate. Why? Because Delboeuf told us so a long time ago with his illusion experiment of thinking the right circle looks bigger:

The portion on the smaller plate will always fill you up more. This can make the difference of an hour of productivity gained each day, simply by reducing the size of your plate and being less full. Joining the small plate movement is definitely something worth trying.

Another aspect comes in regarding the people you are with as Barker points out: "Eating with overweight friends? You'll eat more. Is your waitress overweight? You'll eat more. Are you a woman eating with a man? You'll eat less. Wide variety of food? You'll eat more."

Three most important aspects to get the most out of eating food

It's time to get our hands dirty. I think we've got a basic understanding of how food determines our daily output. But what are the best ways to act on this information?

Reorganize the positioning of food stored in your cupboard: One of the most interesting aspects about eating is that we are extremely likely to eat what is in close sight. In fact, famous researcher Brian Wansink mentions that, "You are three times more likely to eat the first thing you see in your cupboard than the fifth thing you see." Make sure you organize your food in way that brain powering foods get more exposure. It's an incredible trick to start eating better food that will give you more daily alertness.

Learn to graze: From the first section in this post, we've learned that the brain needs very specific portions of food. Too much will give you a spike that rapidly declines. Too little won't bring your brain up to speed. A great way to go about it, I've found, is to make your three daily meals a bit smaller (potentially by making the plates smaller), and then add two very specific, healthy snacks in between meals to keep your brain plugging away at full speed. This way you don't have to change your core habits too much, yet can still fuel up your brain efficiently.

These foods will give your brain the most power: Here is a great list of brain powering foods that you can eat, especially for snacking. The WHO particularly emphasizes the following: dark chocolate, nuts, seeds, and fish.

Some further brain powering foods are the following: blueberries, raw carrots, whole grains, and avocado.

Quick last fact: What you eat will also decide your grandchildren's productivity

As a last quick tip, here is something that blew my mind. Yes, what you eat will affect your productivity today. But even more so, it will determine the productivity of your children and grandchildren's productivity. "Evidence indicates that what you eat can affect your grandchildren's brain molecules and synapses," Gómez-Pinilla said. What you eat can, according to Gomez-Pinilla, rewire your genes, and the more you strengthen the synaptic connections, the better your kids and their kids will perform.

Note: We wrote yesterday about the food organization tricks Leo mentions above. Check out that post here.

Leo Widrich is the co-founder of Buffer, a smarter way to share on Twitter and Facebook. Leo writes more posts on efficiency and customer happiness over on the Buffer blog. Hit him up on Twitter @LeoWid anytime; he is a super nice guy.